Question 657936
>>Sam can type 5 pages in 10 minutes,<<
<pre>
Therefore Sam's typing rate is 5 pages per 10 minutes, or {{{(5_pages)/10_minutes)}}} which is {{{5/10}}}{{{pages/(minute)}}},
or {{{1/2}}}{{{pages/(minute)}}}, 
</pre>
>>Tom can type 10 pages in 5 minutes,<< 
<pre>
Therefore Tom's typing rate is 10 pages per 5 minutes, or {{{(10_pages)/(5_minutes)}}} which is  {{{10/5}}}{{{pages/(minute)}}},
or 2{{{pages/minute)}}}.
</pre>
>>together how many pages can they type in 30 minutes.<<
<pre>
That says:
<font size = 5><b>Together, they can type x pages in 30 minutes.</font></b>

Therefore their combined typing rate is x pages per 30 minutes, or {{{(x_pages)/(30_minutes)}}} or  {{{x/30}}}{{{pages/(minute)}}},

The equation comes from 

          {{{(matrix(7,1,  
"Sam's",typing, rate, in, pages,per, minute))}}} + {{{(matrix(7,1,  
"Tom's", typing, rate, in, pages,per, minute))}}} = {{{(matrix(8,1,  
"Their",combined, typing,rate, in, pages,per, minute))}}} 



                          {{{1/2}}} + 2 = {{{x/30}}}

Multiply through by LCD = 30
                           15 + 60 = x
                                75 = x

So together they can type 30 pages in 75 minutes or 1 hour 15 minutes.

Edwin</pre>